Shaftless electrical control instrumentality



May 19, 1953 w. H. BUDD ET AL SHAFTLESS ELECTRICAL CONTROL INSTRUMENTALITY Filed Nov. 30, 1951 W'LZbari: HBudd 72211; M. UazZy Patented May 19, 1953 SHAFTLESS ELECTRICAL CONTROL INS TRUMENTALITY Wilbert H. Budd and Arthur M. Daily, Elkhart, Ind., assignors to Chicago Telephone Supply Corporation, Indiana Elkhart, Ind., a. corporation of Application November 30, 1951, Serial No. 259,272

9 Claims.

This invention relates to electrical control instrumentalities, and has more particular reference to variable resistance controls of the shaftless type adapted for operation by a screw driver or the like inserted through a hole in the housing of the control device into a drive slot in the contactor assembly to rotate the same.

Variable resistance control devices of this nature generally comprise a housing having spaced apart parallel front and rear walls and a contact assembly inside the housin having a resilient contactor cooperable with a resistance strip and collector ring stationarily mounted in the housing. Because there is no housing journalled operating shaft to support and drive the contactor assembly, its mounting in the housing for rotation relative to the resistance strip and collector ring along with the support of the contactor assembly against the axial thrust of the resilient contactor thereon have constituted problems which hitherto have not been solved without resorting to complicated and costly constructions. Moreover, these problems have been aggravated by the ever increasing demand for greater compactness of such control instrumentalities.

It is the object of this invention, therefore, to provide a shaftless resistance control device of the character described with unusually simple and compact means for supporting the contactor assembly for rotation in the housing of the device and against the axial thrust of the resilient contactor carried thereby.

More specifically, it is the object of this invention to provide a novel thrust bearing for the contactor assembly of a shaftless resistance control device of the character described, which not only supports the contactor assembly against the thrust of the resilient contactor thereon but which also serves to mount the contactor assembly on the housing for rotation within defined limits therein. According to this invention, low cost is also achieved by fabricating the thrust bearing from sheet metal, as a stamping.

With the above and other objects in view, which will appear as the description proceeds, this invention resides in the novel construction and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereinafter disclosed invention may be made as come within the scope of the claims.

The accompanying drawing illustrates one complete example of the physical embodiment of the invention constructed in accordance with the 2 best mode so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a front elevation view of a resistance control device constructed in accordance with this invention, portions thereof being broken away and shown in section;

Figure 2 is a side View of the device shown in Figure 1 but with the front portions of the housing and the parts in its interior shown in section;

Figure 3 is a perspective view of the housing with the rear wall removed and looking at the inner side of the front wall of the housing;

Figure 4 is a perspective view of the thrust bearing per se; and

Figure 5 is a perspective view of the contactor assembly, looking at the front side thereof.

Referring now more particularly to the accompanying drawing, the numeral 5 generally designates the housing of a variable resistance control device of the shaftless type. The housing comprises a cup-like housing part 6 stamped from sheet metal and having a bottom wall I which provides the front wall of the housing, and a cylindrical side wall 8 projecting rearwardly therefrom. The open rear of the housing is closed by a disc 9, of insulating material, which forms the rearwall of the housing.

The rear wall 9, of course, abuts the rim of the cup-like housing part6 and is fixed thereto in any suitable manner as by attaching tabs [0 extending from'the side Wall 8 rearwardly through peripheral notches (not shown) in the rear Wall and bent inwardly over its rear face, as shown best in Figure 2.

Diametrically opposite forwardly extending tabs IZ struck from the front wall I provide for mounting the control device upon the back of a panel l3 (see Figure 2) with registering holes i4 and IS in the front wall of the housing and the panel, respectively, affordin access to the control device from the front of the panel for operation of the device by a screw driver or the like.

The hole 14 is located centrally of the front wall of the housing and is defined by the inner surface of an annular flange l1 integral with the front wall I and extending a short distance rearwardly therefrom. As Will appear hereinafter, the flange 17 preferably has a cylindrical periphery and provides a bearing to rotatably support the contactor assembly l8 of the device.

The contactor assembly l8 comprises a contact carrier 20 in the form of a disc of insulat-' ing material, as seen best in Figure 5, having a ing cooperating contiguous substantially cylindri cally shaped bearing surfaces thereon to mount the rotor assembly on the housing for rotation about an axis normal to the front wall of the housing.

2. In an electrical control instrumentality of the character described: a housing having opposite front and rear walls in fixed spaced apart relationship, the front wall having a central hole therein affordin access to the housing interior, said hole being defined by an inwardly directed annular flange formed on the front wall of the housing; stationary means in the housing fixed to the rear wall thereof; a movable element in the housing intermediate the front and rear Walls thereof and cooperable with said stationary means; means holdin said movable element in cooperating relationship with said stationary means and against forward motion away from the same, comprising a member having a relatively flat wall overlying the front of the movable element, and a number of legs projecting forwardly from said relatively flat wall and engaging the front wall of the housing, said legs being spaced about the axis of the annular flange and slidingly embracing the same to mount said member on the front wall of the housing for rotation about the flange axis; a rotation transmitting connection between said member and the movable element whereby the latter rotates with said member; and means on said flat wall of the member accessible through the hole in the front wall of the housing to provide for the transmission of rotation to said member, and consequently to the movable element of the control instrumentality, from the exterior of the housing.

In an electrical control instrumentality of the character described: a housing having a front wall provided with a central hole therein affording access to the interior of the housing; an annular flange on said front wall extending inwardly into the housing from the edge portions of said hole, said annular flange providing a bearing; a rotatable contact assembly inside the housing including a disc-like contact carrier; means mounting said carrier on the front wall of the housing for rotation about the axis of the annular flange thereon, comprising a member having a Wall portion overlying the front of the carrier and non-rotatably connected thereto, and a series of circumferentially spaced lobes on said wall portion projecting forwardly therefrom and slidingly embracing said annular flange, said lobes having endwise abutting engagement with the front wall of the housing to hold the contact assembly spaced a predetermined distance rearwardly thereof; and means on said member accessible through the hole in the front wall of the housing to provide for the transmission of rotation to the contact assembly.

4. In an electrical control instrumentality of the character described: a housing having opposing front and rear walls in fixed spaced apart relationship, the front wall having a central hole therein affording access to the interior of the housing; an annular flange on said front wall extending inwardly into the housing from the edge portions of said hole, said annular flange providing a bearing coaxial with said hole; stationary means in the housing fixed to the rear wall thereof; and a contact assembly rotata'bly carried by the bearing provided by said annular flange, said contact assembly including a contactor cooperable with said stationary means, and a contact carrier having a drive slot therein accessible through the hole in the front wall of the housing; and spacer means extending between said carrier and the front wall of the housing to preclude forward motion of the contact assembly in the housing and thus hold the contactor in cooperative relationship with said stationary means.

5. The electrical control instrumentality set forth in claim 4 wherein said contact assembly further includes a thrust bearing comprising-a metallic stamping having a relatively fiat body portion overlying the front of the contact carrier and non-rotatably connected thereto, said spacer means being formedintegrally with the body portion of the thrust bearing and comprising a number of circumferentially spaced lobes bent forwardly from the body portion and slidably embracing said annular flange to mount the contact assembly thereon for rotation about the axis of the flange; and said body portion of the thrust bearing having a slot therein registering with the drive slot in the carrier.

6. In an electrical control instrumentality of the character described; a housing having opposing front and rear walls in fixed spaced apart; relationship, the front Wall having a central hole therein affording access to the interior of the housing; flange means on said front wall extending inwardly into the housing from the edge portions of said hole, said flange means having a cylindrical bearing surface thereon to provide a bearing coaxial with said hole; stationary means in the housing fixed to the rear wall thereof; and a contactor assembly rotatably carried by the bearing provided by said flange means, said contactor assembly including a resilient contactor cooperable with said stationary means and tending to urge the contactor assembly forwardly in the housing, and a contact carrier having a drive slot therein accessible through the hole in the front Wall of the housing; and cooperating means on the contactor assembly and the housing for precluding motion of the contactor assembly toward the front wall of the housing under the influence of the contactor so as to thereby hold the contactor assembly in cooperative relationship with said stationary means.

7. In an electrical control instrumentality of the character described: a housing having opposite front and rear Walls in fixed spaced apart relationship, the front wall having a central hole therein providing access to the interior of the housing; cooperating movable and stationary elements in the housing, the latter overlying the inner face of the rear wall of the housing, and the movable element including a resilient contactor exerting a force on the movable element tending to move the same forwardly in the housing; a thrust bearing in the housing for transmitting the forward thrust of the contactor to the front wall of the housing, said thrust bearing comprising a body portion engaged with the front of the movable element and substantially closing said access hole in the front wall, and spacer means extending forwardly from the body portion of the thrust bearing into engagement with the front Wall of the housing; an inwardly extending annular flange on the front wall of the housing adjacent to the edge of the hole therein and coaxial with said hole, said flange cooperating with the spacer means to support the thrust bearing from the front wall of the housing for rotation about the axis of the access hole therein; means on the body portion of the thrust bearing accessible through the hole in the front wall of the housing to provide for the transmission of rotation to the 7 thrust hearing from the exterior of the housing: and e rotation transmitting connection between the thrust bearmg and the movable element whereby the latter rotates with the thrust bearing" 8 The electrical control fnstrumentality set forth in claim '7 wherein said spacer means oomp'rises a number of cireumiferentially spaced lobes on the body portion of the thrust bearing embracing and'rotatably receive-d 'onsaid flange to mount the thrust bearing on the flange forrotation about the axis of the hole in the front wall of the housing, said lobes being bent from the. body portion and having endwlse abutting engagement with the front Wall of the housing directly adja cent to the flange thereon.

9 The eleotrieal control instrumentality set with claim 8 wherein the thrust bearing is prov'lded with at least three such lobes, one of said lobes having itsven'cl portion adjacent to the'front wall of the housing extended and. bent radially outwardly to provide a foot flatwise engaging the adjacent surface of the front wall of the housing; and a stop lug on the outer end of said foot engageable with an abutment on the housing to define the of rotation of the movable element.

WILBERT H. BUDD. ARTHUR M. DAILY.

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